zwitch

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Handle values based on a property.

Install

npm:

npm install zwitch

Use

var zwitch = require('zwitch')

var handle = zwitch('type')

handle.invalid = invalid
handle.unknown = unknown
handle.handlers.alpha = handle

handle({type: 'alpha'})

Or, with a switch statement:

function handle(value) {
  var fn

  if (!value || typeof value !== 'object' || !('type' in value)) {
    fn = invalid
  } else {
    switch (value.type) {
      case 'alpha':
        fn = handle
        break
      default:
        fn = unknown
        break
    }
  }

  return fn.apply(this, arguments)
}

handle({type: 'alpha'})

API

zwitch(key[, options])

Create a functional switch, based on a key (string).

options

Options can be omitted and added later to one.

• handlers (Object.<Function>, optional) — Object mapping values to handle, stored on one.handlers
• invalid (Function, optional) — Handle values without key, stored on one.invalid
• unknown (Function, optional) — Handle values with an unhandled key, stored on one.unknown

Returns

Function — See one.

one(value[, rest...])

Handle one value. Based on the bound key, a respective handler will be invoked. If value is not an object, or doesn’t have a key property, the special “invalid” handler will be invoked. If value has an unknown key, the special “unknown” handler will be invoked.

All arguments, and the context object, are passed through to the handler, and it’s result is returned.

one.handlers

Map of handlers (Object.<string, Function>).

one.invalid

Special handler invoked if a value doesn’t have a key property. If not set, undefined is returned for invalid values.

one.unknown

Special handler invoked if a value does not have a matching handler. If not set, undefined is returned for unknown values.

function handler(value[, rest...])

Handle one value.

Related

• mapz — Functional map

License

MIT © Titus Wormer